Oil cooler



0f- 10, 1944- G. w. ERSTUNG ETAL 2,360,123

OIL COOLER Filed Sept. 18, 19,42 2 Sheets-Sheet 1 (ttomegs Oct. 10, G.w. G ERSTUNG ETAL 2,360,123

v on. cooLER Filed sept. 1s, 1942 2 sheets-sheet 2 .muil www /J Y 3 et rGegfqe 62252221232? 9h/"azze- .Wl/hs@ i ,w Mfg' l attorney Patented et.i0, i944` s Para essaies oFFicE on. cooma George W. Gerstuiig and HiramWalker, Lockport, N. Y., assignors to General Motors Corporation,Detroit, Mich., a corporation et Delaware Application September V18,1942, Serial No. 458,830

2 Claims.

'Ihls invention has to do with heat exchangers and, more particularly,with coolers for the lubrieating oil of the propelling engines andtransmissions of military tanks.

In military tanks, the spaces available for coolers for the lubricatingoil of the propelling engines and transmissions are limited 'and theconditions in'the spaces are not favorable to extraction of heat fromthe oil in the coolers. Consequently, to cool the oil to the requireddegree coolers for the lubricating oil of the propelling engines andtransmissions of military tanks must be highly efficient. To make an oilcooler highly efficient, it is, for well known reasons, necessary toconstruct it so that the oil passages in its core are small in at leastone transverse dimension and oil flows through them not smoothly butturbulently to the extent that when the oil is cold and thick it willnot pass through the passages unless excessive pressure is applied toit.

. The' principal object of this invention is to provide coolers for thelubricating oil of the propelling engines and transmissions of militarytanks which will t into the limited spaces available for them in thetanks and under the unfavorable conditions which obtain in the spacescool the oil circulating through the engines and transmissions to therequired degree whenever and as soon as the oil becomes, and as long asit remains, so hot that cooling of it is necessaryn and yet obviateapplication of excessive pressure to the oil to supply the engines andtransmissions with oil when the oil is cold and thick.

For a better understanding of the nature and objects of this inventionreference is made to the following specification and the accompanyingdrawings in which the preferred embodiment of the invention is describedand illustrated.

Inthe accompanying drawings:

Figure 1 is a side elevation, with parts broken away and in section, ofan oil cooler` in which our invention is embodied.

Figure 2 is an enlarged view of the cooler taken as indicated by theline 2--2 of Figure l.

Figure 3 is a further enlarged section through one of the tubes includedin the cooler taken as indicated by the line 3-3 of Figure 2.

Figure 4 is a still further enlarged fragmentary perspective view of oneof the turbulent plates disposed within the tubes of the cooler.

The oil cooler which is shown in the drawings consists of a core It andoil inlet and outlet nttings II and I2.

The core I includes a number of flat tubes I3 which are disposedparallel to and in registration with each other but spaced apart so thatair-can pass between them. Each of the tubes I3 consists of shallowelongated tray-like member It with a flange on its rim and an elongatedplate I5 whose margin is folded around and metallical- 1y bonded to theflange. Through the bottom of the tray-like member I4 and the plate I5of each tube, except the outermost, there extend near their endscircular openings I6 and Il encircled by anges I 8 and I9 and, betweenthe openings I6 and I1, near the openings I6, elongated openings 20encircled by anges 2l. Corresponding openings are formed in the plate I5of the outermost tube but the tray-like member thereof is leftimperforate.

'I'he tubes I3 are secured together and spaced apart by a plate 22 and adisk 23 between each of the adjacent pairs of tubes. Each of the plates22 is disposed between the openings I 6 and 20 in one of each of theadjacent pairs of tubes and has in it openings 23a and 24 into which aretelescoped the flanges I8 and 2| which encircle the openings I 6 and 20in the tubes. Each of the disks 23 is disposed between the openings I'Iin one of each of the adjacent pairs of tubes and has in it an opening25 into which are telescoped the anges I9 which encircle the openingsI'I in thetubes. Each of the plates 22 and disks 23 is; of course,metallically bonded to the tubes between which it is disposed. Betweeneach of the adjacent pairs of tubes I3 there is disposed a corrugatedsheet whose crests are metallically bonded tothe tubes betweenrwhich itis disposed and which serves to expedite the transfer of heat from theoil owing through the tubes to the air passing between the tubes.

To the plate I5 of the'innermost of the tubes I3 there are metallicallybonded a plate 26 and a disk 2l which are similar to but heavier thanthe plates 22 and disks 23. The plate 26 is disposed over the openingsI5 and 20 inthe plate It and has in it openings 2B and 29 into which aretelescoped the anges I8 and 2| which encircle the openings I6 and 20 inthe plate I5. The disk 2l is disposed over the opening I'I in the plateI5 and has in it an opening 30 into which is telescoped the ilange i9which encircles the opening Il in the plate I. On the disk 21 is mountedthe inlet iitting Ii which has in it a passage 3I which communicateswith the opening 30 in the disk 21. On the plate 26 is mounted theoutlet tting I2 which hasin it passages 32 and 33 which at one endcommunicate with the openings 28 and 29 in the plate 26. At its otherend the passage 33 opens into the passage 32 through a port 34 in thewall which separates the passages. In the passage 32 there is disposed abellows thermostat 35 with a frusto-conical valve 36 on its free `endwhich seats in the -port 34 when the thermostat is hot and extended andis unseated when the thermostat is cold and contracted and thus closes.the port 34 when the thermostat is hot and opens it when the thermostatis cold.

On the plate 22 and the disk 23 between the innermost pair of tubes I3there are provided wings 31 to which areIl secured brackets 38 by whichthe oil cooler may be mounted on a suitable support. Between thebrackets 38 and wings 31 are disposed plates 39, on which there areportions of reduced thickness which underlie the flange on the innermosttube and thusv obviate crushing of the ends of the innermost tube as aresult of handling of the inlet and outlet fittings.

A strip of metal 4I shaped like an elongated hairpin is disposed withineach of the tubes I3 and metallically bonded to the tray-like member I4and plate I5 thereof with its open end near and facing the opening I1and the opening 20 within its confines near its closed end. Withinv theduct 42 defined by the hairpin-like member 4I, there is disposed a stripof metal 43 square- S-shaped in cross section which extends from nearthe opening to near the opening I1 and is metallically bonded to thetray-like member I4, the plate I5 and the hairpin-like member 4I ytoprevent distortion of the tube by internal pressure.

Within each of the tubes I3 on each side of the hairpin-like member 4Ithere is disposed a turbulent plate 44. Between the sides and ends ofthe turbulent plates andthe rim of the tray-like member of al1 of thetubes I3, except the innermost, there are disposed locating andreinforcing strips 45 and 46 which are metallically bonded to thetray-like member and plate of the tube. Between the ends of theturbulent plates and the rim of the tray-like member of the innermost ofthe tubes I3 there are also disposed locating and reinforcing strips 46which are metallically bonded to the tray-like member and plate of thetube but the turbulent plates in this tube are wide enough to extend/tothe rim of the tray-like member of the/tube and there are no locatingand reinforcing strips corresponding to the locating and reinforcingstrips 45 in the other tubes init.

Each of the turbulent plates 44 consists of a sheet of metal deformed toprovide in it transversely corrugated strip-like elements 41 whichextend lengthwise of the plate and are disposed edge to edge with thecorrugations in alternate elements arranged crosswise of the plate inrows displaced lengthwise of the plate from the corrugations in theother elements a distance equal to aboutvone-half of the length of acorrugation. The corrugations in the elements 41 are approximatelyrectangular in contour and are flat crested and the adjoining elementsof each plate are, except where the crests of their corrugationsoverlap, separated from each other to provide openings 48 through whichoil may pass from one corrugation to another lengthwise of the plate.The crests of the corrugations in the turbulent plates 44 aremetallically bonded to the tray-like member and the plate of the tube I3within which the turbulent plates are disposed and, in addition to thefunction indicated by their name, the turbulent plates also serve totransmit heat from the oil Within the tube to the tray-like member andplate of the tube I3 within which they are disposed and to preventdistortion of the tube by internal pressure.

The oil cooler shown in the drawings and hereinbefore described wasdesigned for installation in the lubrication system of the engine ortrans-l mission of a military tank so oil enters it byA way of the inletfitting II and leaves itA by way of the outlet fitting I2. vThe oilwhich enters the cooler passes from the inlet tting I.I into the ductdefined by the openings I1 in the tubes I3 and, thence, into the tubesI3. The oil may pass through and from the tubes I3 into the outletfitting I2 by either of two paths. One is by Way of the ducts 42 definedby the hairpinlike members 4I, the duct defined by the openings 20 inthe tubes I3 and the passage 33 in the outlet fitting I'2. The ducts 42,which are more resistive to the passage of oil than any other part ofthe path, are of such size and character that oil, even when cold andthick, may pass through them without application of excessive pressureto it. The other path is by Way of the passages in the tubes I3v on thesides of the ducts 42 in which are disposed the turbulent plates 44, theduct defined by the openings I6 in the tubes I3 and the passage 32 inthe outlet tting I2. The turbulent plates 44 increase to a highvalue'the efiiciency of transfer of heat from the oil Within thepassages in which they are disposed to the outer Walls of the tubes I3.But, although they do not render the passages in which they are disposedso resistive to the passage of oil that oil cannot when itis hot andthin pass quite freely through them, without application to it ofgreater pressure than normallyv obtains in the lubricating system of theengine or transmissions in which the coolers are installed, theturbulent plates do inherently render these passages so resistive to thepassage of oil that when the oil is cold and thick it cannot passthrough them unless excessive pressure is applied to it.

When the oil is hot and thin, as it ordinarily will be when the engineand transmission have been operating for some time, the thermostat 35will be extended and the port 34 closed by the valve 35. Under thiscondition, the oil will be constrained to take the path last mentionedthrough which it can pass quite freely under the influence of thepressure which normally obtains in the lubricating system, and will behighly efficiently cooled in the course of its passage through thecooler.

'Howeven when the oil is coldk and thick, as it ordinarily will be whenthe engine and transmission have not been operating for some time or maybecome as a result of over-cooling, the thermostat 35 will be contractedand the port 34 open. Under this condition, the oil will naturally takethe path first mentioned through which it even when cold and thick canpass without application of excessive pressure to it. Thus it is assuredthat, even when the oil is cold and thick the engine or transmissionWill be supplied with oil without application of excessive pressure tothe oil.

While the oil passes through the cooler by Way ducts and, consequently,by the time the oil circulating through the engine or transmissionbecomes so hot and thin that cooling of it is necessary the oil in thepassages last mentioned will be warm and thin enough that it can passtherethrough without the application of excessive pressure to it. Whenthe oil circulating through the engine or transmission becomes so hotand thin that cooling of it is necessary the thermostat 35 will extendand seat the valve 36 in and close the port 34. Thereafter, the oil willpass through the cooler by way of the path whichv includes the passagesin the tubes I3 on the sides of the ducts 42 and, consequently, becooled to the necessary extent. If the oil, thereafter, becomesover-cooled and thick, the thermostat 35 will contract and unseat thevalve 3B whereupon passage of oil through the cooler by way of the pathwhich includes the duct 42 will re-commence and continue until the oilagain becomes so hot and thin that cooling of it is necessary. It will,of course, be understood that movement of the valve 36 to and from thepositions in which the 'port 34 is closed and fully'open takes place,not instantaneously, but gradually, and consequently, when the oil isbetween hot and cold it will pass through the cooler in part by way ofone and in part by way of the other of the mentioned paths and maycontinue to do this for 'an extended period if cooling of only a part ofthe oil is required to bring perature.

We claim:

1. In a temperature regulator for ui'ds like lubricating oils whoseviscosities increase when their temperatures decrease,.a plurality of atmembers within each of which there are ducts which extend lengthwise ofand from one to the opposite side wall of the member and through whichthe iiuid may ow when it is hot but oier undue resistance to passage ofthe uidwhen it is cold. the .members being disposed substantiallyparallel to and in registration with each other but spaced apart so thatiiuid may flow between and around them in heat exchanging relation toiuid in the speciiied ducts within them, a duct within each of themembers which extends lengthwise of and from one to the opposite sidewall of the t member between the iirst specied ducts and through whichthe iirst mentioned iluid may when it to its optimumtem-V it is warm owin heat exchanging relation to the uid in the rst specified ductswithout encounteging undue resistance, a duct which extends through theseveral members near corresponding ends of the members and communicateswith the ducts within the members, a duct which extends through theseveral members near the other ends of the members and communicates withthe second specied ducts within the members, a duct which extendsthrough the several members between the two ducts last specified andcommunicates with the second speciiied ducts within them, and meansmovable from a position in which it 'permits passage of the llrstmentioned iiuid through the second specied ducts within the members andthe last specified duct when it is cold to a position in which itobstructs passage of the rst mentioned fluid through the-last mentionedducts when it is hot.

2. In a temperature regulator for fluids like lubricating oils whoseviscosities increase when their temperatures decrease, a flat hollowmember, a. member generally square-S-shaped in cross section which isdisposed within and extends lengthwise of the fiat hollow member betweenits edges and divides the interior of the flat hollow member into ductswhich extend lengthwise of and from one to the opposite side wall of thenat hollow member on each side of the member which is generallysquare-S-shaped in cross section and through which the uid may flow whenit is hot but offer undue resistance to passage of the uid when it iscold and ducts which extend lengthwise of and from one to the oppositeside wall of the flat hollow member between the first mentioned ductsand through which the first mentioned uid may when it is warm flow inheat exchanging relation to the uid in the first mentioned ducts withoutencountering undue resistance, the iat hollow member being disposed sothat Iluid may flow around it in heat exchanging relation to the iiuidin the rst mentioned ducts .and means movable from a position in whichit permits passage of the iirst mentioned iiuid through the-secondmentioned ducts when it is cold to a position in which it obstructspassage of

